Hairdryer with high electrical safety

ABSTRACT

A hairdryer includes a casing, a flow duct provided within the casing and having an intake port and a delivery port, a motor unit including an electric motor, and at least one rotor, which can be driven in rotation by the electric motor and is configured for sucking in an air flow through the intake port and sending it into the flow duct towards the delivery port. At least one electrical resistance is inserted in the flow duct and configured for heating the air flow taken in by the aforesaid rotor. The at least one electrical resistance is coated with electrically insulating material, and the motor unit includes a watertight casing housing the electric motor.

TECHNICAL FIELD

A hairdryer including:

a casing,

a flow duct provided in said casing and having an inlet port and anoutlet port,

a motor unit including an electric motor,

at least one rotor operable in rotation by means of said electric motorand configured for sucking in an air flow through said inlet port andsend it into said flow duct towards said outlet port,

at least one electrical resistance inserted into said flow duct andconfigured for heating the air flow taken in by said rotor.

PRIOR ART

Currently known hairdryers are afflicted by a fundamental problem ofsafety, due to the presence of live parts that are completely exposed tothe external environment, and in so far as they are likely to comeaccidentally into contact with water, thus causing an electric shockthat is potentially lethal for the user.

In addition to the well-known accident due to accidental fall of ahairdryer in a bath or a washbasin, there is a further and moredangerous form of accident due to accidental entry of water into thehairdryer when it is not being used. In these circumstances, in the casewhere the user, unaware of infiltration of water, were to reactivate themotor of the hairdryer, a shortcircuit would be triggered in theresistance that heats the air, in the motor, or worse still in thepushbuttons of the hairdryer, causing a potentially lethal electricshock.

OBJECT OF THE INVENTION

The object of the present invention is to solve the technical problemsdescribed previously. In particular, the object of the present inventionis to provide a hairdryer that will be intrinsically safe for the usereven following upon conditions that might cause an accident of anelectrical nature due to accidental contact with water.

SUMMARY OF THE INVENTION

The object of the present invention is achieved by a hairdryer havingall the features listed at the outset of the present description, andmoreover characterized in that:

said at least one electrical resistance is coated with electricallyinsulating material; and

said motor unit includes a watertight casing housing said electricmotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the annexeddrawings, which are provided purely by way of non-limiting example andin which:

FIG. 1 is a perspective partial see-through view of a hairdryeraccording to various preferred embodiments of the invention;

FIG. 2 is a longitudinal cross-sectional view according to the traceII-II of FIG. 1;

FIG. 3 is a perspective view of internal components of the hairdryer ofFIGS. 1 and 2;

FIG. 4 is a perspective view of a casing of a motor unit of thehairdryer according to the invention; and

FIGS. 5 and 6 are perspective views according to the arrows V and VI ofFIG. 4, respectively.

DETAILED DESCRIPTION

The reference number 1 in FIG. 1 designates as a whole a hairdryeraccording to various embodiments of the invention.

The hairdryer 1 includes a casing 2, which develops along a longitudinalaxis X1 and provided within which is a flow duct 4.

The flow duct 4 is in fluid communication with the external environmentby means of an intake port 41N and a delivery port 4OUT. Within the flowduct 4 there are arranged, all coaxial to the axis X1, a rotor 6 and amotor unit 8 including an electric motor M configured for driving therotor 6 in rotation about the axis X1.

The rotor 6 can be driven in rotation for sucking in an air flow throughthe port 41N and sending it through the flow duct 4 towards the port4OUT.

Moreover provided within the flow duct 4 is at least one electricalresistance, which is configured for heating the air flow drawn in by therotor 6. In the embodiment represented in the figures, the hairdryer 1includes a first electrical resistance 10 and a second electricalresistance 12, both obtained by means of a nickel-chromium steel wirewound in a cylindrical and/or conical helical path.

Each of the resistances 10, 12 is coated with an electrically insulatingmaterial resistant to high temperatures, for example Teflon. Theresistances 10, 12 are coated throughout their development.

Each of the resistances 10, 12 is supported radially by means of aplurality of ribs 14 of thermoinsulating material, for example mica.Each of the ribs 14 includes a substantially T-shaped coupling profileT14. With reference to FIG. 2, the ribs 14 are fixed to the motor unit 8by means of the profiles 14T.

The motor unit 8 includes a watertight casing 16, with the electricmotor M enclosed within the watertight casing 16 itself. The casing 16includes a first shell 18 having a substantially hollow ogival shape, aseal 19 (for example, an annular seal of an O-ring type), and a secondshell 20. The seal 19 is set between the shells 19 and 20 to guaranteewater tightness at the interface between them. The motor M is fixed bymeans of screws to the shell 18.

Each of the shells 18, 20 is provided with a plurality of radial eyeletsspaced at equal angular spaces apart, which are designated,respectively, by the reference numbers 18A, 20A. These radial eyeletsare used for fixing of the ribs 14, and in particular for coupling withthe profiles T14, which are configured for engaging in the eyelets 18A,20A and for being withheld radially by them thanks to the undercutoffered by the T-shape.

In particular, the coupling between the shells 18, 20 is obtainedaxially along the axis X1 with interposition of the seal 19 and with themotor M already inside the casing 16, then the shells 18, 20 arefastened together by means of screws S that engage, in correspondingsequences, two axial holes (one smooth and one threaded), one for eachof the shells 18, 20.

Preferably, the shell 20 is provided with an array of radial vanes 21,which are configured for co-operating with the rotor 6 for regularizingthe air flow within the flow duct 4. Moreover, the radial vanes areconfigured for acting as cooling fins for dissipating the heat generatedby the electric motor M.

The shell 20 is substantially cup-shaped and includes a first radialextension 22 configured for fixing it to the casing 2, and a secondradial extension 24 having within it a channel 26 configured for routingone or more electrical wiring systems that carry the supply to the motorM.

The radial extension 24 moreover passes through the casing 2 and isconnected thereto through a seal 28, which eliminates the possibility ofpenetration of water into the interface between the casing 2 and theextension 24. In a position corresponding to the radial extension 24there is preferably provided a handle (not visible) by means of whichthe user can grip the hairdryer during use and inside which theelectrical wiring coming out of the channel 26 is routed. Once againpreferably, on the handle a set of pushbuttons may be provided byco-injection of silicone in order to maintain water tightness.

The shell 20 moreover includes a through hole coaxial to the axis X1,which is traversed by an output shaft 30 of the motor M, fitted on whichis the rotor 6. As may be seen in FIGS. 4 and 6, the shell 20 is closedat the end by a watertight cap 31 that fits on the shaft 30 so as toguarantee water tightness also at the (sliding) interface with the shaft30. In particular, the cap 31 incorporates a watertight bearing(preferably, a ball bearing) configured for receiving the output shaft30 and for ensuring water tightness between the latter and the secondshell 20.

At the opposite end, the shell 16 also includes a through hole coaxialto the axis X1 fitted in which is a plug-like seal 32, which couples ina watertight way with the hole in the casing 16. The plug-like seal 32includes one or more pairs of through orifices configured for beingtraversed by the wires that constitute the electrical resistances 10, 12in such a way that the latter can penetrate within the casing 16 and beincorporated with the wiring that is routed in the channel 26 withoutjeopardizing water tightness of the casing 16 itself.

In the embodiment illustrated, the resistances 10, 12 are obtained bymeans of a single wire wound twice, a first time to form the resistance10 and a second time to form the resistance 12, so that only twoportions of wire traverse the seal 32. In other embodiments, theresistances 10, 12 may be provided by means of separate wires—forexample, to envisage a differentiated supply thereof in order to varythe heat power, and consequently the temperature of the air—so thatthere will be two pairs of portions of wire that traverse the seal 32.

It should be noted that, in alternative embodiments, it may be possibleto exclude from the coating just the portion of wire that constitutesthe electrical resistances intended to penetrate into the casing 16,since this portion of wire would in any case be located in anenvironment that is in itself watertight.

In the preferred embodiment illustrated herein, moreover set inside theflow duct 4 of the hairdryer is a sleeve 34 having a shape thatpreferably reproduces, albeit on a smaller scale, the shape of the wallsof the casing 2.

The sleeve 34 is located in particular in a position comprised betweenthe electrical resistances 10, 12 and the wall of the casing 2, withrespect to which it is supported by means of a plurality of radial ribs36, preferably obtained in an integral way with the casing 36.

In this way, the flow duct 4 is split (albeit not necessarily throughoutthe length of the casing 2: this depends upon the axial extension of thesleeve 34 with respect to the casing 2) into a main duct definedsubstantially inside the sleeve 34, within which find the electricalresistances 10, 12 and at least part of the watertight casing 16 of themotor unit 8 are located, and a secondary flow duct, which has anannular cross section and is set around the sleeve 34, in particularbetween the latter and the casing 2.

During operation, driving in rotation of the rotor 6 via the electricmotor M of the motor unit 8 causes intake of an air flow through theintake port 4IN. This air flow is split into two fractions on account ofsplitting of the path of the flow duct 4. In particular, a first amountof flow—the larger amount—traverses the main duct and impinges upon theelectrical resistances 10, 12, which are supplied electrically, like themotor M, through the bundle of wiring that traverses the channel 26,penetrating into the casing 16, so that the air flow that comes out ofthe delivery port 4OUT will have a higher temperature than the air flowdrawn in through the port 4IN.

A second amount of air flow—the smaller amount—passes into the secondaryduct, eliminating the moisture that might be present within the casing 2and cooling the casing 2 as a whole, thus enabling installation ofelectrical resistances of higher power in the case where the applicationwere so to require. This moreover enables thermal insulation of the areaoccupied by the resistances through a curtain of cool air generated bythe intake within the secondary duct. This solution keeps the wholecasing 2 cooled and at the same time improves the air flow, in a way atleast roughly resembling the effect exerted by the so-called Vortexwinglets typical of a wing profile.

The set of measures of electrical protection adopted on the hairdryer 1,which render the live parts thereof completely insulated from contactwith water, prevents any risk of electric shock for the user also in thecase of circumstances that might potentially cause an electric shock,such as in the case where the hairdryer were accidentally to fall intowater or if water happens to infiltrate into the hairdryer when it isnot being used.

In particular, all the electrically supplied parts, namely the motor Mand the electrical resistances 10, 12, are in effect electricallyinsulated from the external environment thanks to:

coating the surface of the resistances 10, 12 with electricallyinsulating material; and

producing the casing 16 of the motor unit 8 as a watertight casing byproviding the gaskets 19, 32, 28 and the cap 31.

In this way, in the case where a jet of water were to hit the hairdryer1, it would at the most manage to impinge on the shell 16 withoutpossibly penetrating therein, and would likewise be able only to impingeon the electrically insulating coating of the resistances 10, 12,without coming into contact with the electrically conductive material.Hypothetically, thanks to these measures, the hairdryer 1 could evenfunction completely immersed in water without suffering any damage andwithout inflicting any harm on the user.

Of course, in alternative embodiments, it is possible to eliminate thesleeve element 34, thus obtaining a single-walled flow duct. In thisway, the entire air flow drawn in by the rotor 6 would come to impingeon the resistances 10, 12, without exerting a cooling action proper onthe walls of the casing 2.

Of course, the details of construction and the embodiments may varywidely with respect to what has been described and illustrated herein,without thereby departing from the scope of the present invention, asdefined by the annexed claims.

1. A hairdryer including: a casing, a flow duct provided in said casingand having an inlet port and an outlet port, a motor unit including anelectric motor, at least one rotor operable in rotation by said electricmotor and configured for sucking in an air flow through said inlet portand sending the air into said flow duct towards said outlet port, atleast one electrical resistance inserted into said flow duct andconfigured for heating the air flow taken in by said rotor, said atleast one electrical resistance is coated with an electricallyinsulating material, and said motor unit including a watertight casinghousing said electric motor.
 2. The hairdryer according to claim 1,wherein each electrical resistance of said at least one electricalresistance is made by a wire-like element coated with an electricallyinsulating material.
 3. The hairdryer according to claim 1, wherein saidwatertight casing includes a first shell and a second shell joined toone another with a seal therebetween.
 4. The hairdryer according toclaim 3, wherein said second shell includes a radial extension having achannel therein for the routing of electrical cables configured forpowering said electric motor and said at least one electricalresistance.
 5. The hairdryer according to claim 4, wherein said radialextension is connected to said casing with an interposed seal.
 6. Thehairdryer according to claim 3, wherein said first shell includes an endhole into which a plug-like seal fits traversed by wire-like membersdefining said at least one electrical resistance so as to route saidwire-like members into said watertight casing.
 7. The hairdryeraccording to claim 3, wherein each of said first and second shellsincludes a plurality of radial eyelets configured for coupling with acorresponding plurality of support ribs for said at least one electricalresistance, wherein said support ribs are bound to said first and secondshells upon the joining thereof in an axial direction.
 8. The hairdryeraccording to claim 3, wherein said second shell is traversed by anoutput shaft of said electric motor whereon said rotor is fitted, a capincluding a watertight bearing that supports said output shaft and isconfigured for providing a watertight seal between said output shaft andsaid second shell being furthermore coupled to said second shell.
 9. Thehairdryer according to claim 1, further including a sleeve arranged intosaid casing and providing a splitting of the path of said flow duct intoa main duct, wherein said at least one electrical resistance is housed,and a secondary duct having an annular cross section comprised betweensaid sleeve and a wall of the casing.
 10. The hairdryer according toclaim 9, wherein said rotor is configured for sending a first share ofthe inlet air flow into said main duct so as to impinge upon said atleast one electrical resistance, and a second share of the inlet airflow into said secondary duct so as to cool the casing, said first sharebeing a major share.